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Quick Start Guide
4.3
Configuring the signal output fail-safe (Rising or Falling)
The NAMUR electronics indicates a covered or uncovered fork sensor state
by one of two switched output currents and the on-board LED. As a fail-safe,
the PCB can be configured to indicate either state when there is a fault.
Falling arrow fail-safe
When the Rosemount 2521 is used to indicate a full-silo, set the PCB switch
to the Falling Arrow fail-safe position. A power failure or line break is
regarded as a full-silo signal (for protection against overfilling).
Rising arrow fail-safe
When the Rosemount 2521 is used to indicate an empty load, set the PCB
switch to the Rising Arrow fail-safe position. A power failure or line break is
regarded an as empty-silo signal (as protection against running dry).
Figure 4-3: Rising and Falling Fail Safe Settings
A. Rising Arrow fail-safe (switch position up)(default)
B. Falling Arrow fail-safe (switch position down)
26
A
B
October 2020
Quick Start Guide
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